Douglas Pallett, 60, of Colchester, Essex, bombarded fellow Conservative supporter Lynda Guglielmi with obscene and racist mail after their two- year affair ended, Chelmsford Crown Court in Essex, was told.
John Caudle, prosecuting, said Pallett's campaign took place between January 1996 and May 1997. Had it occurred later he would have been prosecuted under new stalking legislation, said Mr Caudle.
Jurors also heard that he daubed obscene graffiti around a school where Mrs Guglielmi chaired the governors, and placed cards in telephone kiosks giving her number or address and advertising her services as a prostitute.
Mrs Guglielmi, who is in her mid-40s, and is a parish councillor in Lawford, near Colchester, Essex, shook and cried as she described her 18-month "nightmare" to the jury of eight men and four women.
The prosecution alleged that Pallett caused Mrs Guglielmi injury by making her clinically depressed. Mrs Guglielmi told how the ordeal had changed her from a "calm, controlled" woman into a "neurotic" who was depressed and still needed help from a counsellor.
She said Pallett - a former Essex county councillor and district councillor in Manningtree - was "obsessive, mad" and "off his rocker".
She told the court that she first met Pallett at local political functions in Essex - both were members of the North Colchester Conservative Association.
They began an affair in April 1993. Both were married at the time - Mrs Guglielmi to her husband Carlo, from whom she is now divorced, and Pallett to his wife Lesley, from whom he is separated.
Mrs Guglielmi said she had not had sex with her husband for more than seven years when the affair began and did not feel that she was "cheating". Her husband had accepted the situation, she said.
The affair ended in May 1995, Mrs Guglielmi added.
Pallett denies causing either grievous bodily harm or actual bodily harm to Mrs Guglielmi.Reuse content